According to NHANES data, the prevalence of obesity in the U.S. population has increased from 25 percent to 33 percent over the past 10 years. Obesity is well accepted as a risk factor for coronary heart disease and type 2 diabetes, and it exacerbates many chronic conditions such as hypertension and dyslipidemia. Not surprisingly, the economic costs of obesity are staggering and amount to approximately 100 billion dollars annually. The prevalence of obesity appears to be proportionately greater in certain minority populations. Almost twice as many African-American women are overweight compared to Caucasians. Moreover, the disproportionate levels of obesity in African-American women may have their origins in childhood and adolescence. Approximately 30 percent of African-American girls between the ages of 6 and 17 years are overweight, compared to only 22 percent for all other youth as a whole. Large prevention trials, most notably, the Child and Adolescent Trial for Cardiovascular Health (CATCH) and the Dietary Intervention Study in Children (DISC), have been largely unsuccessful in producing reductions in dietary fat, body weight or BMI. Thus, the NHLBI has proposed a research program to develop and test interventions to prevent weight gain in preadolescent African-American girls. The Biostatistics Center of the George Washington University proposes to serve as the Coordinating Center for this project. In this role, we will attend to the following functions. (1) Study Coordination and Planning: We will help establish an efficient organizational structure to ensure that all activities advance in a coordinated fashion. (2) Data Management Activities: We will apply our Distributed Data Entry system for on-going data collection and generate periodic reports summarizing the execution of the trial. (3) Statistical Analysis: We will provide statistical leadership in the design of the study, and perform interim and final analyses in an expeditious and timely manner.